奇怪的数 参考代码

#include <bits/stdc++.h>
using namespace std;

typedef long long LL;
const LL MOD = 998244353;
const int maxn = 10;
int n, m;
LL ans;
LL dp[2][maxn][maxn][maxn][maxn];

int main() {
#ifdef ExRoc
    freopen("test.txt", "r", stdin);
#endif  // ExRoc
    ios::sync_with_stdio(false);

    cin >> n >> m;
    for (int a = 1; a < 10; a += 2) {
        for (int b = 0; b < 10; b += 2) {
            for (int c = 1; c < 10; c += 2) {
                for (int d = 0; d < 10; d += 2) {
                    if (a + b + c + d <= m) {
                        dp[0][a][b][c][d] = 1;
                    }
                }
            }
        }
    }

    for (int i = 5; i <= n; ++i) {
        int nowi = (i % 2);
        int prei = nowi ^ 1;
        memset(dp[nowi], 0, sizeof(dp[nowi]));
        for (int e = nowi; e < 10; e += 2) {
            for (int d = nowi ^ 1; d < 10; d += 2) {
                for (int c = nowi; c < 10; c += 2) {
                    for (int b = nowi ^ 1; b < 10; b += 2) {
                        for (int a = nowi; a < 10; a += 2) {
                            if (a + b + c + d + e > m) {
                                continue;
                            }
                            dp[nowi][b][c][d][e] =
                                (dp[nowi][b][c][d][e] + dp[prei][a][b][c][d]) %
                                MOD;
                        }
                    }
                }
            }
        }
    }

    for (int a = 0; a < 10; ++a) {
        for (int b = 0; b < 10; ++b) {
            for (int c = 0; c < 10; ++c) {
                for (int d = 0; d < 10; ++d) {
                    ans = (ans + dp[n & 1][a][b][c][d]) % MOD;
                }
            }
        }
    }
    cout << ans << endl;

    return 0;
}